Can't find the 'libpq-fe.h header when trying to install pg gem

Question

I am using the Ruby on Rails 3.1 pre version. I like to use PostgreSQL, but the problem is installing the pg gem. It gives me the following error:

$ gem install pg
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
    ERROR: Failed to build gem native extension.

        /home/u/.rvm/rubies/ruby-1.9.2-p0/bin/ruby extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/home/u/.rvm/rubies/ruby-1.9.2-p0/bin/ruby
    --with-pg
    --without-pg
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config


Gem files will remain installed in /home/u/.rvm/gems/ruby-1.9.2-p0/gems/pg-0.11.0 for inspection.
Results logged to /home/u/.rvm/gems/ruby-1.9.2-p0/gems/pg-0.11.0/ext/gem_make.out

How do I solve this problem?

Solution 1

It looks like in Ubuntu that header is part of the libpq-dev package (at least in the following Ubuntu versions: 11.04 (Natty Narwhal), 10.04 (Lucid Lynx), 11.10 (Oneiric Ocelot), 12.04 (Precise Pangolin), 14.04 (Trusty Tahr) and 18.04 (Bionic Beaver)):

...
/usr/include/postgresql/libpq-fe.h
...

So try installing libpq-dev or its equivalent for your OS:

• For Ubuntu/Debian systems: sudo apt-get install libpq-dev
• On Red Hat Linux (RHEL) systems: yum install postgresql-devel
• For Mac Homebrew: brew install postgresql
• For Mac MacPorts PostgreSQL: gem install pg -- --with-pg-config=/opt/local/lib/postgresql[version number]/bin/pg_config
• For OpenSuse: zypper in postgresql-devel
• For ArchLinux: pacman -S postgresql-libs

Solution 2

On macOS (previously Mac OS X and OS X), use Homebrew to install the proper headers:

brew install postgresql

and then running

gem install pg

should work.

Alternatively, instead of installing the whole postgresql, you can brew install libpq and export the correct PATH and PKG_CONFIG_PATH as explained in the 'Caveats' section

Solution 3

I had also tried doing gem install libpq-dev, but I received this error:

Can't find the 'libpq-fe.h header
*** extconf.rb failed ***

However I found that installing with sudo apt-get (which I try to avoid using with Ruby on Rails) worked, i.e.

sudo apt-get install libpq-dev
# or
apt-get install postgres-server-dev-{pg.version}
# for postgresql 9.4 on Ubuntu 14.04

then I was able to do

gem install pg

without issues.

Solution 4

I could solve this in another way. I didn't find the library on my system. Thus I installed it using an app from PostgreSQL main website. In my case (OS X) I found the file under /Library/PostgreSQL/9.1/include/ once the installation was over. You may also have the file somewhere else depending on your system if you already have PostgreSQL installed.

Thanks to this link on how to add an additional path for gem installation, I could point the gem to the lib with this command:

export CONFIGURE_ARGS="with-pg-include=/Library/PostgreSQL/9.1/include/"
gem install pg

After that, it works, because it now knows where to find the missing library. Just replace the path with the right location for your libpq-fe.h

Solution 5

Can't find the libpq-fe.h header

i had success on CentOS 7.0.1406 running the following commands:

~ % psql --version # => psql (PostgreSQL) 9.4.1
yum install libpqxx-devel
gem install pg -- --with-pg-config=/usr/pgsql-9.4/bin/pg_config

Alternatively, you can configure bundler to always install pg with these options (helpful for running bundler in deploy environments),

• bundle config build.pg --with-pg-config=/usr/pgsql-9.4/bin/pg_config

View more solutions

Comments

[Michael Durrant]

didn't work for me on ubuntu 11.04 durrantm@castleLinux2011:~/Dropbox_not_syncd/webs/3/linker$ gem install libpq-dev ERROR: Could not find a valid gem 'libpq-dev' (>= 0) in any repository durrantm@castleLinux2011:~/Dropbox_not_syncd/webs/3/linker$

[mu is too short]

Right, the Ruby pg gem wraps the usual PostgreSQL C libraries that come with the Ubuntu/Debian/... libpq-dev package.

[Nick Woodhams]

If you then are required to have a javascript library installed... gem install 'execjs' and gem install 'therubyracer'

[mu is too short]

@TravisR: Thanks for the update, I just turned this into a community wiki to make it easier for everyone to keep it up to date.

[vedarthk]

I am using Ubuntu 12.10, I am not able to install pg gem after installing libpq-dev

[mu is too short]

@vedarthk: What does "not able" mean? Perhaps a new question with the install logs would get you the help you need.

[vedarthk]

@muistooshort Yes I have posted the question : stackoverflow.com/q/14477825/1277376

[Jiemurat]

Thanks, sudo apt-get install libpq-dev helped me

[Jason Kim]

Works with Ubuntu 12.04 64 bit

[Hanxue]

In Mac OS X, get homebrew from brew.sh , then brew install postgres to install PostgresQL and its header files.

[Ryan Spears]

David's solution worked for me. I tracked libpq-fe.h to '/Applications/Postgres.app/Contents/Versions/9.3/include' and used the export command with said path, followed by the 'gem install pg' and the gem installed successfully.

[Dawei Yang]

Using macports, sudo port install postgresql-devel.

[Sebastialonso]

Works like a charm in centOS 6.5

[brookr]

Thanks for this, worked for me, using: export CONFIGURE_ARGS="with-pg-include=/usr/local/Cellar/postgresql‌​/9.3.1/include/"

[furiabhavesh]

"libpq-dev: /usr/include/postgresql/libpq-fe.h" is present whereas "postgres-xc-server-dev: /usr/include/postgres-xc/server/gtm/libpq-fe.h" is not present ? what am I missing ?

[Vincent Fourmond]

File contents may have changed. This looks like there was a private copy of libpq-fe.h in the postgres-... package. In any case, the libXXX-dev is the one you're looking for if you want to compile things.

[iconoclast]

Does this cause any problems if you're also using Postgres.app?

[iwasrobbed]

@iconoclast I use Postgres.app to run a db instance so having the pg gem just allows you to hook your Rails app up to your local Postgres.app instance

[overallduka]

For me after run brew install postgressql i run ARCHFLAGS="-arch x86_64" gem install pg and works fine.

[Yi Zeng]

Upvoted. I installed Postgresql via EnterpriseDB's grapihcal installer. Then I need to find out the pg-config path by sudo find / -name "pg_config", then do gem install pg -- --with-pg-config=/Library/PostgreSQL/9.4/bin/pg_config using the path I have just found out.

[fearmint]

Using Postgresql 9.3 on CentOS 6 I solved this by symlinking the pg_* scripts into the $PATH like so: ln -s /usr/pgsql-9.3/bin/p* /usr/local/bin. I installed postgres 9.3 like so: yum install http://yum.postgresql.org/9.3/redhat/rhel-6-x86_64/pgdg-redh‌​at93-9.3-1.noarch.rp‌​m && yum install postgresql93 postgresql93-contrib postgresql93-server postgresql93-devel

[fearmint]

How did you install postgres? I symlinked the pg_* scripts into the path like so: ln -s /usr/pgsql-9.3/bin/p* /usr/local/bin. After that I didn’t need any additional scripts or environment variables.

[Ricardo Saporta]

Alternatively, just running brew install libpqxx on mac OSX suffices

[lfender6445]

you can also write as gem install pg -- with-pg-include=/Library/PostgreSQL/9.1/include/

[Zoidrums]

Please revise your answer to include apt-get install postgres-server-dev-{pg.version} Your answer no longer works with postgresql 9.4 on Ubuntu 14.04 See: stackoverflow.com/a/28837453/75194

[mu is too short]

@RyanRauh: Can you submit an edit? I'm not using Ubuntu right now so I'm not really qualified to say much here.

[Les Nightingill]

very helpful, thanks. Just to add a note regarding bundle config... you must run this command while logged-in as the user who will be running the subsequent bundle command. The bundler config is stored in ~/.bundle/config, so it will not be found if you run bundle config while logged-in as root, but bundler is being run by (e.g. with capistrano) the 'deploy' user.

[Shelvacu]

I just had a probelm with this because I was confusing g and q. to be clear, the package wanted is libpq-dev with a Q not a G

[liloargana]

bundle config build.pg --with-pg-config=/usr/pgsql-9.4/bin/pg_config solve i for me on Centos 7

[Michael Lafayette]

I tried to do that on Ubuntu 14.04 but it gave me this: " libpq-dev : Depends: libpq5 (= 9.3.4-1) but 9.3.10-0ubuntu0.14.04 is to be installed.

[Michael Lafayette]

But then when I try to install libpq5, it says "libpq5 is already the newest version. Same for PostgreSQL."

[Michael Lafayette]

PostgreSQL version is: psql --version: psql (PostgreSQL) 9.3.10. PostgreSQL 9.3.10 on x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2, 64-bit.

[Michael Lafayette]

The following packages have unmet dependencies: postgresql-server-dev-9.3 : Depends: libpq-dev (>= 9.3~) but it is not going to be installed E: Unable to correct problems, you have held broken packages.

[mu is too short]

@MichaelLafayette I don't have Ubuntu set up anywhere right now so I don't know what the problem could be.

[dworrad]

You can also install specific versions with yum - yum install postgresqlxx-devel e.g yum install postgresql94-devel

[mzalazar]

After installing libraries... do a clean up: "make distclean", "make clean", "./configure" and start compiling!

[troex]

port select --set postgresql postgresql96 or any other version you installed to active symlinks including pg_config

[jamesxu-e.g.]

While I executed the command : sudo apt-get install libpq-dev, I get a response - "Unable to locate package". So I execute sudo apt-get update, then executed "sudo apt-get install libpq-dev". Finally it successfully installed.

[Troggy]

@RicardoSaporta libpqxx installs postgresql as dependency, so it is essentially the same as brew install postgresql

[Oleksii Kyslytsyn]

it helped to recover back to initial ruby distribution from rvm but not fixing the problem.

[Master of Ducks]

Works great if you're using the wonderful Postgres.app. For Postgres 10, I used the path /Applications/Postgres.app/Contents/Versions/10/bin/pg_confi‌​g

[Mahesh Neelakanta]

bundle config build.pg --with-pg-config=/usr/pgsql-10/bin/pg_config if you are using postgresql10

[Jagdish]

"brew link --force postgresql" worked for me but befor that i have to run 'export PATH="/usr/local/opt/[email protected]/bin:$PATH"' >> ~/.bash_profile

[Andy Ray]

Why do gem designers rely on implicit, undocumented, globally installed dependencies, and make no attempt to check for their existence before installing the gem?

[mu is too short]

@AndyRay But they are checking for dependencies, that's what "checking for pg_config" and "checking for libpq-fe.h" are about. There's no way to check if the PostgreSQL development stuff is installed without, well, installing some scripts that look for the standard PostgreSQL dev tools (such as pg_config or the header file). Same thing happens when you need anything that isn't packaged inside a gem.

[goetzc]

Instead of installing the whole postgresql, you can brew install libpq and export the correct PATH and PKG_CONFIG_PATH as explained in the 'Caveats' section.

[skozin]

Better yet, use export CONFIGURE_ARGS="with-pg-config=/path/to/postgres/bin/pg_conf‌​ig". The pg_config executable will be called to get all the required compiler and linker options — you can run it yourself to see them.

[Alex Poca]

If it is not enough, add sudo apt-get install postgresql before libpq-dev

[Sopalajo de Arrierez]

Ubuntu/Debian systems solution valid for Raspbian v9.9 on Raspberry Pi devices.

[Jaydeep]

I tried the same steps but still getting error in Redhat: Building native extensions. This could take a while... ERROR: Error installing pg: ERROR: Failed to build gem native extension. current directory: /opt/chef/embedded/lib/ruby/gems/2.5.0/gems/pg-1.1.4/ext /opt/chef/embedded/bin/ruby -r ./siteconf20190924-18624-nckmb.rb extconf.rb checking for pg_config... yes Using config values from /bin/pg_config checking for libpq-fe.h... *** extconf.rb failed ***

[Alexis Wilke]

Without a -- before the --with-pg-config=... I get an error: ERROR: While executing gem ... (OptionParser::InvalidOption) invalid option: --with-pg-config=/usr/bin/pg_config)

[Chris Vilches]

This worked for me, I already had installed Postgres, and I just needed to execute sudo apt-get install libpq-dev then bundle install and the error disappeared. Thanks

[Roel Van de Paar]

So once found, what is the next step?

[Vincent Fourmond]

apt-get install the_package_you_found

[Roel Van de Paar]

And ls /usr/include/postgresql/libpq-fe.h /usr/include/postgresql/pg_config can be used to check the files are there to start with.

[8bitme]

This also sorted it for me on Ubuntu 20.04 using Linuxbrew. sudo apt-get install libpq-dev kept failing because of some other dependency

[lacostenycoder]

Thank you, this was only one that worked for me!

[DisplayMyName]

Doesn't let me edit your answer, you missed a letter, it should be libpq5-devel. It helped though, thanks.

[A. Rosas]

I swear I had noticed that and fixed it but I guess I just thought about it. Thanks for pointing it out.

[Augusto Samamé Barrientos]

I would love to buy you a beer sometime. This is the ONLY thing that worked in Centos 7/8 after hours struggling with it

[johnpitchko]

David's version didn't work for installing an old version of the gem (0.21), but @skozin's instruction did. Thank you!

[magni-]

Note: /<path>/.asdf/installs/postgres/<version> is returned by asdf where postgres

[Exodus Reed]

this worked perfectly for me on ubuntu 20.04 LTS. Thank you!

[Manuel Lazo]

worked like a charm! sudo apt-get install libpq-dev && cd project-directory && bundle install .

[shikharraje]

As someone who's just been hired to work with Ruby/Rails for the first time... Are there many more issues like this? Where a build requires a database installation to run? Do Ruby builds keep breaking for random reasons like this?

[pachi]

Thanks! It worked for me on Fedora 35

[jdempcy]

@iconoclast I can confirm this does not cause problems with Postgres.app. I've installed Postgres.app and done 'brew install postgres' on two Macs now, in order to get around the problem of pg not installing due to missing headers. Both times worked great, and allow successful bundle install or gem install pg. No need for specifying --with-pg-config, that was a red herring for me.

[Phil]

For postgres 12 and above I had to do yum install libpq5-devel